Betelgeuse has been shrinking continuously since 1993, at an increasing rate. By June 2009, it had shrunk 15% from its size as measured in 1993.

But wait! There's more. It is rumored, though I have been unable to find any reliable confirmation of the source (which is claimed to be first-hand) that the latest observations from Mauna Kea show that Betelgeuse is now shrinking so fast it is no longer round. (Due to conservation of angular momentum, when a massive star collapses gravitationally, it collapses faster at the poles, becoming increasingly oblate — flattened — as its final collapse accelerates.)

What does this mean?

Well, briefly, what it means — if true — is that Betelgeuse could be within as little as weeks of a Type II (core collapse) supernova. (Astronomers have considered for some time that Betelgeuse has the potential to go supernova any time in the next thousand years or so. "Any time" may just turn out to be rather sooner than expected.)

IF this happens, not to put too fine a point on it, it will almost undoubtedly be among the most dramatic astronomical events ever observed by human eyes. A type II supernova can briefly outshine an entire galaxy ... and this one will be only a little over five hundred LY away. The supernova that created the Crab Nebula, SN 1054, was bright enough to see in daylight for 23 days, and remained visible for 653 days ... and it was 6,300 LY away. Betelgeuse is almost 12 times closer, and can be expected to appear around 140 times brighter by virtue of that alone. And as noted at the beginning of this post, Betelgeuse is the ninth largest star known to exist in the universe.

If the rumor is true, this is going to be one hell of a show, and we'll have a front-row seat.